SIGNL4 website screenshot

SIGNL4

SIGNL4 is a mobile alerting and on-call duty management service that transforms emails, webhooks, and IoT events into reliable push, SMS, and voice alerts with acknowledgement tracking, escalation, and team on-call scheduling. The platform provides both an inbound webhook for sending alerts and a REST API for managing alerts, statuses, annotations, and team data. Authentication uses a team or webhook secret embedded in the URL path or supplied via the X-S4-Api-Key header.

SIGNL4 publishes 2 APIs on the APIs.io network: Events API and Webhook API. Tagged areas include Alerting, Incident Management, On-Call, Mobile Alerts, and Notification.

SIGNL4’s developer surface includes authentication, documentation, pricing, signup flow, support, engineering blog, GitHub presence, and 5 more developer resources.

🌐 Visit website 📡 Source on GitHub
37.9/100 thin ▬ flat Agent 19/100 agent aware saas Full breakdown ↓
scored 2026-09-14 · rubric v0.22.0
1 APIs
AlertingIncident ManagementOn-CallMobile AlertsNotificationDevOpsIT OperationsMonitoring

Kin Score

Kin Score Kin Score How this is scored →
scored 2026-09-14 · rubric v0.22.0
Composite quality — 37.9/100 · thin
Contract Quality 13.4 / 23
Developer Ergonomics 6.4 / 18
Access Clarity 5.7 / 18
Operational Transparency 0.6 / 12
Contract Governance 0.0 / 11
Discoverability 6.2 / 9
Create-or-Update Ergonomics 2.8 / 10
Agent readiness — 19/100 · agent aware
Machine-Readable Contract 18 / 18
Agentic Access Contract 10 / 10
Documented Reversibility 0 / 6
MCP Server 0 / 12
Machine-Readable Auth 10 / 10
Idempotency 0 / 9
Stable Error Semantics 0 / 8
Request/Response Examples 7 / 7
Rate-Limit Signaling 0 / 7
Typed Event Surface 0 / 6
Agent Skills 0 / 5
Well-Known Catalog 0 / 4
Consent & Bot Identity 0 / 3
A2A Agent Card 0 / 8
Dry-Run / Simulate Mode 0 / 4
Delegated User Identity 0 / 6
Protected Resource Metadata 0 / 5
Registration Without a Human 0 / 6
Agentic Commerce Well-Known Document 0 / 5
Create-or-Update Ergonomics applies to this provider. This API accepts writes, so it carries 10 points of the composite. It is scored from the published contracts themselves: whether a caller can create-or-update in one call, whether the write accepts a key the caller already holds, and whether the response says which branch ran. Without that, every write needs a search-and-branch in front of it, and the first time that check is skipped a duplicate record is created. Scored against the observed mean rather than raw — a provider at the catalog average is unchanged by this facet, not penalised by it.
Improve this rating by publishing the missing artifacts — every area above can be raised, and the full rubric is at apis.io/rating/. Every facet and dimension name above is a link: it opens that measurement's own page — what it means, the exact checks that feed it, how the whole catalog distributes on it, and the providers at the top of it. This rating is computed from github.com/api-evangelist/signl4: open an issue to ask a question, or submit a pull request to add artifacts. Submit an artifact on GitHub — free → Manage your own listing — the Influence plan, $499/mo →

APIs 4

Individual APIs this provider publishes, each with its own machine-readable definition.

SIGNL4 Inbound Webhook API

Simple HTTPS webhook endpoint for triggering mobile alerts in SIGNL4 from any monitoring, ITSM, or IoT tool. Accepts JSON payloads with Title and Message fields plus optional X-...

SIGNL4 REST API

RESTful API for programmatic alert lifecycle management including creating events, acknowledging or closing alerts, annotating alerts, and retrieving team data. Authentication i...

SIGNL4 Events API

The Events API from SIGNL4 — 1 operation(s) for events.

SIGNL4 Webhook API

The Webhook API from SIGNL4 — 1 operation(s) for webhook.

Open Collections 4

Open, tool-agnostic API collections (OpenAPI-derived and Bruno).

API Collection

OPEN COLLECTION

SIGNL4 Webhook and REST Events API

OPEN COLLECTION

SIGNL4 and REST Events Webhook API

OPEN COLLECTION

SIGNL4 Webhook and REST API

OPEN COLLECTION

Security Posture 3

Authentication, domain security, vulnerability disclosure, and trust-center signals.

Signl4 Authentication

apiKey · 1 scheme

SECURITY

Signl4 Domain Security

TLSv1.3 · DMARC

SECURITY

Signl4 Trust Center

ISO 27001, GDPR

SECURITY

Agentic Access 1

Recommended x-agentic-access execution contracts for AI agents.

Signl4 Agentic Access

2 operations · 2 acting

2 operations · 2 acting

AGENTIC

Resources

Get Started 1

Portal, sign-up, and the first successful call

Signup
Signup

Documentation 1

Reference material describing how the API behaves

Documentation
Documentation

Agent Surfaces 1

MCP servers, agent skills, and machine-readable catalogs

AgenticAccess
AgenticAccess

Build 1

SDKs, sample code, and the tooling you integrate with

GitHub
GitHub

Access & Security 3

Authentication, authorization, and security posture

TrustCenter
TrustCenter
 DomainSecurity
DomainSecurity
 Authentication
Authentication

Operate 1

Status, limits, changes, and where to get help

Support
Support

Commercial 1

Pricing, plans, and the legal terms of use

Pricing
Pricing

Company 3

The organization behind the API

LinkedIn
LinkedIn
 Website
Website
 Blog
Blog

Source (apis.yml)

apis.yml Raw ↑ 
aid: signl4
name: SIGNL4
description: SIGNL4 is a mobile alerting and on-call duty management service that transforms emails, webhooks, and IoT events
  into reliable push, SMS, and voice alerts with acknowledgement tracking, escalation, and team on-call scheduling. The platform
  provides both an inbound webhook for sending alerts and a REST API for managing alerts, statuses, annotations, and team
  data. Authentication uses a team or webhook secret embedded in the URL path or supplied via the X-S4-Api-Key header.
type: Index
deliveryModel:
  model: saas
  open_source: false
  commercial: true
  callable_host: true
  label: Hosted service · you call their endpoint
  confidence: high
  source:
  - openapi
  - pricing
  generated: '2026-08-28'
  method: derived
accessModel:
  pricing: unknown
  onboarding: unknown
  trial: false
  try_now: false
  public: false
  label: Unknown
  confidence: low
  source:
  - authentication
  - security
  generated: '2026-09-03'
  method: derived
image: https://kinlane-images.s3.amazonaws.com/shared/apis-json/icons/signl4.png
tags:
- Alerting
- Incident Management
- On-Call
- Mobile Alerts
- Notification
- DevOps
- IT Operations
- Monitoring
tags_raw:
- Alerting
- Incident Management
- On-Call
- Mobile Alerts
- Notifications
- DevOps
- IT Operations
- Monitoring
url: https://raw.githubusercontent.com/api-evangelist/signl4/refs/heads/main/apis.yml
created: '2026-05-11'
modified: '2026-05-11'
specificationVersion: '0.23'
apis:
- aid: signl4:inbound-webhook
  name: SIGNL4 Inbound Webhook API
  description: Simple HTTPS webhook endpoint for triggering mobile alerts in SIGNL4 from any monitoring, ITSM, or IoT tool.
    Accepts JSON payloads with Title and Message fields plus optional X-S4 control parameters for service categorization,
    location, alerting scenario, and external identifiers. Authentication uses a unique team or webhook secret embedded in
    the URL path.
  humanURL: https://docs.signl4.com/integrations/webhook/webhook.html
  baseURL: https://connect.signl4.com/webhook
  tags:
  - Webhook
  - Inbound
  - Alerting
  - Mobile Push
  properties:
  - type: Documentation
    url: https://docs.signl4.com/integrations/webhook/webhook.html
  - type: APIReference
    url: https://connect.signl4.com/webhook/docs/index.html
  - type: CodeExamples
    url: https://github.com/signl4/code-snippets
- aid: signl4:rest-api
  name: SIGNL4 REST API
  description: RESTful API for programmatic alert lifecycle management including creating events, acknowledging or closing
    alerts, annotating alerts, and retrieving team data. Authentication is via X-S4-Api-Key header with the team or webhook
    secret.
  humanURL: https://docs.signl4.com/integrations/rest-api/rest-api.html
  baseURL: https://connect.signl4.com/api
  tags:
  - REST
  - Alert Management
  - Event
  - Incident Response
  tags_raw:
  - REST
  - Alert Management
  - Events
  - Incident Response
  properties:
  - type: Documentation
    url: https://docs.signl4.com/integrations/rest-api/rest-api.html
  - type: Overview
    url: https://www.signl4.com/webhook-rest-smtp-api-integration/
  - type: CodeExamples
    url: https://docs.signl4.com/samples/code-samples/code-samples.html
- aid: signl4:signl4-events-api
  name: SIGNL4 Events API
  description: The Events API from SIGNL4 — 1 operation(s) for events.
  humanURL: https://docs.signl4.com/integrations/webhook/webhook.html
  baseURL: https://connect.signl4.com/webhook
  tags:
  - Event
  tags_raw:
  - Events
  properties:
  - type: OpenAPI
    url: openapi/signl4-events-api-openapi.yml
- aid: signl4:signl4-webhook-api
  name: SIGNL4 Webhook API
  description: The Webhook API from SIGNL4 — 1 operation(s) for webhook.
  humanURL: https://docs.signl4.com/integrations/webhook/webhook.html
  baseURL: https://connect.signl4.com/webhook
  tags:
  - Webhook
  properties:
  - type: OpenAPI
    url: openapi/signl4-webhook-api-openapi.yml
common:
- type: AgenticAccess
  url: agentic-access/signl4-agentic-access.yml
- type: TrustCenter
  url: security/signl4-trust-center.yml
- type: DomainSecurity
  url: security/signl4-domain-security.yml
- type: Authentication
  url: authentication/signl4-authentication.yml
- type: LinkedIn
  url: https://www.linkedin.com/company/signl4
- type: Website
  url: https://www.signl4.com
- type: Documentation
  url: https://docs.signl4.com
- type: Pricing
  url: https://www.signl4.com/pricing/
- type: Signup
  url: https://account.signl4.com/register
- type: Support
  url: https://support.signl4.com
- type: Blog
  url: https://www.signl4.com/blog/
- type: GitHub
  url: https://github.com/signl4
maintainers:
- FN: Kin Lane
  email: kin@apievangelist.com

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